Scientists Solve Venus Cloud Puzzle Using Simple Fluid Dynamics

The next-closest planet to the Earth is Venus, which remains surrounded by dense clouds of sulfuric acid. It had mystified researchers for many years until recently why such a large cloud system existed around Venus, measuring some 3,700 miles wide and orbiting the planet in just a few days' time, with a remarkably sharp leading edge. It turns out that the answer is related to simple physical processes occurring in your kitchen sink!

A Solar System Record-Breaker

Reported in the Journal of Geophysical Research: Planets, scientists from the University of Tokyo have employed numerical simulations to reveal how an extremely large atmospheric wave front can be generated by a major hydraulic jump, where a fast and shallow fluid flow decelerates and thickens, like water flowing from a tap forming on the bottom surface of the sink basin. On Venus, a planetary Kelvin wave travels eastwards within the lower clouds of Venus, destabilises, and induces a powerful localised updraft, lifting vapourised sulfuric acid to much higher altitudes. The vapour rises about 31 miles high and forms a massive cloud front.

Why It Matters Beyond Venus

This marks the first hydraulic jump ever found beyond Earth — and the largest known anywhere in the solar system. The discovery also sheds light on another enduring Venusian puzzle: Venus's clouds super-rotate about 60 times faster than the planet turns. The momentum carried by the Kelvin wave is transferred to the mean flow through the hydraulic jump, contributing to the maintenance of this extreme atmospheric superrotation — a coupling absent from all existing climate models. Incorporating it will demand considerable supercomputing power, but promises to significantly sharpen preparation for future Venus missions and our broader understanding of planetary atmospheres.